1. Field of the Invention
The present invention concerns an oil-in-water emulsion preparation containing alcoholic, homeopathic and/or herbal active ingredients.
2. Background Information
Preparations applied to the skin (dermatics) with homeopathic or herbal active ingredients are distinguished in that they only contain a few adjuvants that are natural in origin. No stabilizers, antioxidants and preservatives should be used. The creation and composition of such preparations are described in detail in the Homeopathic Pharmacopoeia (HAB). For example in regard to ointments, it prescribes (according to specification 13) that water-containing wool-wax alcohol ointment as per the German pharmacopoeia (DAB) is to be used as a base, i.e., a vehicle for the active ingredient(s). If other bases are used, they must be stated. The homeopathic active ingredient(s) are incorporated into the base. Such water-in-oil or oil-in-water emulsion preparations, termed xe2x80x9cW/Oxe2x80x9d and xe2x80x9cO/W emulsion preparationsxe2x80x9d in the following are frequently physically instable when the homeopathic active ingredients are added in the form of mother tinctures and/or dilutions due to the alcohol content (especially ethanol content) of the mother tinctures/dilutions. There hence exists a need for other preparations that have a sufficiently high alcohol and especially ethanol tolerance and are permitted by the HAB.
Normally, emulsifiers are used to stabilize O/W emulsion preparations. These usually low-molecular substances can interact with the skin due to their amphiphile structure [Ashton P., et al., xe2x80x9cEffects of surfactants in percutaneous adsorption,xe2x80x9d pharm. Acta Helv. 61 (8), 228-235, 1986] and hence generate incompatibility reactions such as toxic-irritating reactions or contact allergies.
State-of-the-art suitable adjuvants for stabilizing certain specific emulsions are in particular cellulose ethers, so-called polymer emulsifiers. They are suitable for stabilizing these certain emulsions since they are adsorbed at O/W interfaces, lower the interface tension between the outer and inner phase, and form stabile interface films [Barta A. and Daniels R., xe2x80x9cPharmacopoeial cellulose ethers as o/w emulsifiersxe2x80x94I. Interfacial properties,xe2x80x9d Eur. J. Pharm. Biopharm., 40, 128-133. (1994)]. Cellulose ethers enjoy widespread use as adjuvants in certain pharmacy and foods technology. In solid drug forms, they are used as a binder for granules, a matrix former for the delayed release of active ingredients, and as a film former that is dissolved by stomach and intestinal juices. In liquid preparations, they primarily serve to increase viscosity of eye drops; at higher concentrations, they also serve as a hydrogel former. It has been determined that cellulose-ether-containing preparations are well-tolerated in eyes. There are no known undesirable side-effects on the skin for this class of substances.
The use of various cellulose ethers to stabilize alcohol-free O/W emulsions has been investigated in recent years where particularly positive results were obtained with hypromellose-stabilized O/W emulsions that contain medium-chain triglycerides as an oil phase [Rimpler S. and R. Daniels, xe2x80x9cEffect of oil content on the properties of emulsions containing HPMC as polymeric emulsifier,xe2x80x9d Proc. 1st World Meeting APGI/APV, Budapest, 9/11 May 651-652, (1995)].
In addition to the problem of satisfactory stabilization, another problem with O/W emulsion preparations is that water-containing preparations tend to be susceptible to microbial attack. Germs can be introduced during manufacture and during use by the patient. The use of preservatives in such preparations is therefore appropriate, but preservatives can trigger incompatibility reactions in patients and are preferably avoided for this reason.
An object of the present invention is to present well-tolerated and sufficiently preserved emulsion preparations as a base for homeopathic mother tinctures and dilutions, liquid plant extracts and ethanolic tinctures. The vehicles should have very few adjuvants that are preferably described in the pharmacopoeias (Pharmacopoia Europa (Ph Eur), German Pharmacopoeia (DAB), Homeopathic Pharmacopoeia (HAB), United States Pharmacopoeia (USP)) in a monograph and are hence judged harmless; it should be easy to prepare and incorporate the active ingredient(s) in a laboratory and on a mass-production scale.
The present invention provides an O/W emulsion preparation containing an alcohol and an homeopathic and/or other herbal active ingredient, the preparation being characterized in that it contains cellulose ether as an additive.
The cellulose-ether-stabilized, oil-in-water emulsion preparations containing active ingredient in alcohol (i.e.: containing alcohol and homeopathic and herbal active ingredient(s)) are distinguished primarily in that they are surprisingly very stable in storage. This storage stability is clearly greater than would be expected based on state-of-the-art professional knowledge on hypromellose-stabilized emulsions. The present invention is based on the surprising insight that adding alcohol and especially ethanol substantially improves the storage stability of hypromellose-stabilized emulsions. This insight contrasts with the predominant opinion of the professional world up to now that asserts that O/W emulsions become unstable with the addition of alcohol-containing liquids such as liquid homeopathic tinctures and dilutions, or plant extracts in alcohol.
In addition, the O/W emulsion preparations according to the present invention have the advantage that the emulsion is sufficiently preserved, and other preservatives do not need to be added at a correspondingly high alcohol concentration (especially ethanol concentration) of e.g. 15 mass percent (% m/m).
Another advantage of the O/W emulsion preparations according to the present invention is that they are substantially easier to prepare in contrast to conventional alcohol-free and ethanol-free emulsions; the polymer emulsifiers can disperse without being heated to high temperatures by adding alcohol-containing or ethanol-containing active ingredient to the preparation and/or the adding pure ethanol.
The problem on which the present invention is based is also solved by the presentation of a procedure to create a cellulose-ether-containing O/W emulsion preparation containing homeopathic and/or herbal active ingredients in alcohol that is characterized by the number and series of the procedural steps below:
1. The cellulose ether(s) is/are dissolved in the alcoholic-aqueous emulsion phase, and
2. The cellulose-ether-containing alcoholic-aqueous emulsion phase obtained in this manner is then homogenized with the oil (oil phase).
This preparation procedure according to the present invention has advantages over conventional procedures: It is much faster since only two procedural steps are required whereas the conventional procedure has four steps, and less energy must be expended because the emulsion no longer has to be heated to disperse the polymer emulsifier.
The following cellulose ethers, by themselves or together and preferably in an amount of 0.1 to 10 mass percent (in reference to the overall mass of the emulsion preparation), that are used to prepare the cellulose-ether-stabilized, active-ingredient-containing emulsion preparations according to the present invention are preferably:
Methylcellulose Ph Eur
Hydroxypropylcellulose Ph Eur
Hypromellose (syn Methylhydroxypropylcellulose) Ph Eur
Methylhydroxyethylcellulose Ph Eur
Hydroxyethylcellulose Ph Eur
Sodium carboxymethylcellulose Ph Eur.
Suitable dispersed phases of the O/W emulsion preparations according to the present invention are in particular the following oils, individually or together, and preferably in an amount of 1 to 74 mass percent (in reference to the overall mass of the emulsion preparation):
Medium-chain triglycerides Ph Eur
Peanut oil Ph Eur
Castor oil Ph Eur
Highly liquid paraffin Ph Eur
Highly viscous paraffin Ph Eur.
Suitable active ingredients of the emulsion preparations according to the present invention are homeopathic mother tinctures and dilutions, liquid alcoholic plant extracts and other alcoholic and especially ethanolic tinctures. They are preferably used in an amount of 1 to 50 mass percent (in reference to the overall mass of the emulsion preparation).
To further increase the storage stability and resistance to microbial attack, the emulsion preparations according to the invention can have ethanol, preferably in an amount of 1 to 20 mass percent (in reference to the overall mass of the emulsion preparation) in addition to the alcoholic active ingredients.
All the emulsion preparations according to the present invention are quite suitable for preparing homeopathic and/or phytopharmaceutic drugs. The present invention therefore also concerns homeopathic and/or herbal drugs that have been prepared using an emulsion preparation according to the present invention.